Evaporation is a process of disposing a substance to be formed as a film in vacuum to evaporate/sublimate and precipitate on a surface of a substrate or work piece. Heating evaporation material and plating it on the substrate is called vacuum evaporation or vacuum plating. Vacuum plating process is widely used in manufacturing processes of devices (such as display panels).
A mask is used for covering a certain area of a glass substrate in an evaporation process of a display panel, so that the evaporation material is precipitated in the uncovered area to form a film. Theoretically, a surface of the mask should be parallel to the glass substrate. In this case, a result of the evaporation should correspond to the mask exactly, and be consistent with the design.
In practice, however, a central area of the mask will be significantly deformed, because edges of the mask are fixed on a supporting frame, and the mask is ultrathin (thickness of the mask is dozens of micrometers) and suffered imbalanced forces. Under influence of the deformation, the film formed on the glass substrate deviates from an expectation situation, leading to bad evaporation effect of the evaporation device. Further, if the mask suffers a force in a vertical direction which varies greatly in the process of fixing the mask, the mask will impact the glass substrate with a very high velocity, thereby causing the glass substrate and the mask to be damaged. Furthermore, if the mask suffers a force in the horizontal direction, a problem of scratching photo spacers on the glass substrate may be caused.